The big change here is obviously the Material design UI. Google Wallet doesn't have too many layers involved, so you don't quite get the sense of depth; but, you will get the slide out navigation menu, bold colors, and a few nice new animations. That said, there are a few new proper features for you in this update. You can now set up automatic transfers from your bank account, so you'll always have money in your Wallet account. Additionally, you can set up alerts for when your Wallet balance hits a certain threshold. Lastly, you can lock or cancel your physical Google Wallet card from within the app, just in case you misplace it.
The update started rolling out on Android yesterday, which means it should find its way to everyone within a week or so. But, the update should be live for iOS users now.
source: Google Commerce Blog